Palaeontographical Society Monographs Volume 28, Nos. 127-129

Palaeontographical Society Monographs Volume 28, Nos. 127-129

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1874 edition. Excerpt: ...equal to more than half the length, and situated over the arterior hinge. Anterior extremity broadly rounded; posterior somewhat narrower and rectangularly truncate; superior margin nearly straight, highest in front; inferior slightly sinuated, the whole circumference being much jagged and spinous. Outline, as seen from above, ovate, extremities obtuse. The shell of 'the male is longer, narrower, and distinctly 'quadrangular, and 'its infero-posteal angle is produced into a more or less conspicuous squamous and spinous plate. The surface of the shell is marked by large subhexagonal excavations, the intervals between which are beset with 'several strong spines of irregular shape and size, which are much larger in the male than in the female; there is also a row of spinous tubercles parallel to and a little within the anterior margin, the series being continued with less regularity along the greater part of the ventral margin. Hinge-tubercles large, shining, and prominent, especially in the male. Hinge-teeth very strongly developed, shell very thich and strong. ' ' Length, qlgth of an inch. (73/i/tere Dunelmensis is not very rare in the living state in the seas of Norway, Scotland, and Northern England, mostly inhabiting depths of fifteen fathoms and upwards. The reticulation of the surface is often obscure, and its spinous armature is very variable in strength and general development. Young specimens (fig. 19) are subovate in form, with the margins arched and the angles well rounded off. The form figured in Plate XI, figs. 36, 37, which we at one time supposed to belong to a distinct species, is without doubt the young stage of C'. Dzmelmensis; between this and the adult form almost all gradations of growth...show more

Product details

  • Paperback | 134 pages
  • 189 x 246 x 7mm | 254g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 123688549X
  • 9781236885494